Synthesis/degradation of glycogen is tightly regulated
Mathematical modelling predicts a maximal value for the particle size above which further growth is impossible as there would not be sufficient space for interaction of the chains with the catalytic sites of glycogen metabolism enzymes. This generates a particle consisting of 12 tiers corresponding to a 42 nm maximal diameter including 55,000 glucose residues. 36% of this total number rests in the outer (unbranched) shell and is thus readily accessible to glycogen catabolism without debranching. In vivo, glycogen particles are thus present in the form of these limit size granules (macroglycogen) and also smaller granules representing intermediate states of glycogen biosynthesis and degradation (proglycogen). Glycogen particles are entirely hydrosoluble and, therefore, define a state where the glucose is rendered less active osmotically yet readily accessible to rapid mobilization through the enzymes of glycogen catabolism as if it were in the soluble phase.
Synthesis of glycogen requires priming by
Taken together, these studies found that tightly regulated control of both synthesis and degradation allows rapid changes in the level of KLF13 in human T lymphocytes.",}
Glycogen synthesis begins with a freely reversible isomerisation reaction catalysed byphosphoglucomutase:glucose-6-phosphateglucose-1-phosphateThe next reaction, the UDP-glucose pyrophosphorylase reaction:glucose-1-phosphate + UTPUDP-glucose + PPiis essentially irreversible, because pyrophosphatases in the cell catalyse the irreversible hydrolysisof:PPi2Pipulling the equilibrium over to the right.